I've been searching through all the threads I could find regarding a sheet metal cone, but I can't quite find what I'm trying to do.  Not being a sheet metal guru by any means, I may be going about this all wrong, so I'm hoping someone here can set me straight.  I'm trying to create a sheet metal cone with an overlapping seam - I can get close, but I always wind up with something blowing up - either a flat pattern or the loft itself.  Seems I can get a loft, but not a flat pattern.  The attached file sets up a theoretical cone with 1/8" thick sheet metal, (in reality, it'll probably be 24 or 26 gage), but I thought I was accounting for bend allowances, etc but I can't get it to work correctly, what's the best way to construct this thing?

Thanks

Todd